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Three-dimensional model for stellacyanin, a "blue" copper-protein
B A Fields1, J M Guss, H C Freeman
1Department of Inorganic Chemistry, University of Sydney, Australia.
Journal of Molecular Biology
|December 20, 1991
Summary
Researchers modeled stellacyanin, a blue copper-glycoprotein, using computer graphics. The model, based on cucumber basic protein (CBP) homology, explains its spectroscopic properties and redox potential.
Area of Science:
- Biochemistry
- Structural Biology
- Computational Chemistry
Background:
- Stellacyanin is a blue copper-glycoprotein involved in electron transfer.
- Blue copper proteins typically feature a methionine residue coordinating the copper atom.
- Stellacyanin lacks methionine, presenting a unique structural challenge.
Purpose of the Study:
- To derive a three-dimensional model of Rhus vernicifera stellacyanin.
- To rationalize the spectroscopic properties, redox potential, and electron-transfer kinetics of stellacyanin.
- To investigate the copper coordination environment in stellacyanin.
Main Methods:
- Homology modeling using cucumber basic protein (CBP) as a template.
- Computer graphics, energy minimization, and molecular dynamics simulations.
- Analysis of amino acid sequence homology and spectroscopic data.
Main Results:
- A plausible three-dimensional model for stellacyanin was generated.
- The model suggests copper coordination by histidine 46, cysteine 87, histidine 92, and glutamine 97.
- This coordination explains stellacyanin's spectroscopic and redox properties.
Conclusions:
- The derived model provides a rationalization for stellacyanin's unique characteristics.
- Sequence homology is crucial for selecting appropriate templates in homology modeling.
- Computational modeling outputs are highly dependent on input data quality and relevance.